"Current Gap Settings" is also listed but is not really an option, but rather an alias for one of the other 4: the one that is currently selected in the the gap settings. So, creating a CUE sheet with this option will create a file identical to one of the other 4.

In beginner mode, you'll only see two options listed:

Single WAV File

Multiple WAV Files — this is the same as Multiple WAV Files With Gaps (Noncompliant)

Most don't know, but actually the CUE Sheet is just a simple ASCII file, in a format quite easy to read and interpret (if needed you can also edit it).

For the test, the Rush album Signals was used. It was chosen because it has few tracks (8), simple format (7 gaps, all non-zero lengths), no hidden tracks (no index 00 for the 1st track) and standard 2s before the 1st track.

As we can see, this one is pretty straightforward. A single file, assumed by EAC to be Range.wav, is used in all tracks. Track 1 starts with index 1 (a track 1-index 0 would mean a hidden track), at the file's absolute position 00:00:00. All the times are the absolute position within the Range.wav file. Here the tracks (01 indices) and the gaps (00 indices) are so easy to see and figure out that I have nothing much to tell about this format, except that this simple format will help us to understand the basics, and will sure come in hand when things get dicy.

Just a note for future reference: the gap length of a given track can be calculated by subtracting the INDEX 00 start position from its INDEX 01 start position. For example, track 3 gap starts at 10:22:12, and the actual track starts at 10:22:57. That leads us to a 57-12 = 00:00:45 gap.

Note that this CUE is very similar to the previous, the difference being multiple wavs are used. This CUE assumes you appended gaps in the beginning of each track, and that's why, for example, Track 03-Index 00 starts at 00:00:00 of Chemistry.wav. The actual song (index 01) starts at 00:00:45 of that file. This way we can easily see that this pregap is 00:00:45 long.

NOTE: In CUE Sheets and EAC's CD layout window, the time format is Minutes:Seconds:Frames, where 1 frame is 1/75th of a second, not 1/100th of a second. So, a gap displayed 00:00:50 in a CUE sheet does not mean a half-second gap, but rather a two-third-second gap (something like 0.66 or 0.67 in decimal notation).

This one also looks a lot like the previous. The difference is that now indices 01 start at the very beginning of the files (00:00:00). So, where are the gaps? They are artificially inserted with the "PREGAP" tag. PREGAP, as we can assume by reading this file and confirm its behaviour, tells the burner to create a 00 index of the specified length, filled with silence. Note that the INDEX 00 statement can't be used, because its time refers to the wav file, and in this case no gaps were appended anywere on the wavs. They were simply left out. PREGAP puts them back again (you better pray for what was left out was only silence, because that's all you'll get when using PREGAP). EAC's CD Layout Editor clearly shows that the 00 indices were re-created, but not from any wav file. In this format it is easy to see that the track 3 pregap that was removed when extracting the wavs was 00:00:45 long, because that's what the PREGAP statement of track 3 tells us.

The most tricky, yet "right", CUE Format. The 1st file, Subdivisions.wav, is used in both Track1-Index1 and Track2-Index0 (track 2 pregap). This gap starts at 05:33:45 of the file, and last until the end of it. Then, we see the marker of a new file, The Analog Kid.wav. Track 02 Index 01 starts at the beginning of this file, and lasts until 04:47:32, where, while keep reading the same wav file, Index 00 of Track 03 starts to be recorded. This pattern keeps until the end of the album, and we can see that each wav file is used for a track (index 01) and then for a pregap (index 00 of the next track). Using CD Layout Editor makes this tricky "chaining" of tracks and files very easy to see. So this format assumes that the gaps were appended to the end of the previous track. It's not a surprise then that Countdown.wav is only used as Track 08 - Index 01. As there is no track 9 pregap, nothing was appended to it. Its own pregap was appended to the previous file, Losing It.wav.

Now lets try to find our now-famous 00:00:45 gap in this format. We already know that we are looking for Track 03 - Index 00. Looking at the CUE, we find that it is in The Analog Kid.wav file, starting from 04:47:32, and lasting until the end of this file. So we need to know, in a very accurate way, the length of this file.Winamp nor EncSpot? are accurate enough as they only have second precision. But we can again use EAC's CD Layout to manually "Append files as New Tracks" and see the length. And it tells us that "The Analog Kid.wav" is 04:48.16 long. Subtracting the gap's initial position from the file's length leads us to the actual gap length: 04:48:02 - 04:47:32 = 00:00:45!

For this weird math, remember that CUE Sheets use the "75 notation", so from 04:47:32 to 04:48:00 there are 75-32=00:00:43. So we add +2 (from 04:48:00 to 04:48:02), leading us to our so-loved 00:00:45.

By now, I think that this format, as all the other ones, are quite clear. With the info here, one now might be able to, given any CUE, calculate all gap lengths and, if needed, edit the CUE Sheet to convert from one format to the other. Just in case you find out that in your mp3s the gaps were appended in the end of the tracks, as usual, but the CUE you have is the "corrected" one, where gaps are supposed to be at beginning. Now you can, with Notepad, Calculator, and a bit of Brains, (EACs CD Layout Editor may be handy too), convert this cue to the format you want. (in this case, the "Noncompliant").

This article is based on MestreLion's great research posted in the HydrogenAudio forum.

All the knowledge shared here was gained by creating the 4 different cue sheets, opening them in Notepad and comparing them to the content showed in EACs track window. Loading the CUEs into EACs CD Layout Editor also helped a lot, by showing the CUE's content in a more friendly way.